Calcium aluminate is a kind of non-metallic mineral products with alumina and calcium oxide as the main components, mainly used for deoxidation, slag removal, desulfurization and other functions in steelmaking. It has the characteristics of low melting point, low viscosity and good fluidity of slag formed at steelmaking temperature, small erosion of furnace lining and so on. It is a kind of environmentally friendly slagging agent with good effect, and can also be used as a covering agent of molten iron. Using calcium aluminate as slag making agent can choose different types of calcium aluminate according to different steelmaking process and conditions can reduce the oxygen content in steel to 0.002%, sulfur content to 0.003%.